Concentrated ambient PM_2.5 exposure affects mice sperm quality and testosterone biosynthesis

Area of Science:

• Environmental Health
• Reproductive Toxicology
• Toxicology

Background:

• Previous studies indicate PM_2.5 exposure negatively impacts male animal reproduction, but mechanisms remain unclear.
• Limited research exists on PM_2.5 effects in China, where pollution levels and components differ.
• Current exposure methods like intratracheal instillation require improvement for more relevant studies.

Purpose of the Study:

• To investigate the effects of concentrated ambient PM_2.5 (CAP) on male mice.
• To assess CAP's impact on sperm quality parameters.
• To analyze CAP's influence on testosterone biosynthesis and related gene expression.

Main Methods:

• Male C57BL/6 mice were exposed to filtered air (FA) or CAP for 125 days.
• Evaluated sperm concentration, motility, DNA integrity, and plasma testosterone.
• Analyzed testicular histology, sperm morphology, and expression of key testosterone biosynthesis genes via real-time PCR.

Main Results:

• CAP exposure led to abnormal sperm morphology (44.83% vs. 24.37%) and disturbed spermatogenesis.
• Significant decreases in sperm concentration (25.33 × 10⁶ vs. 43.00 × 10⁶) and motility were observed.
• CAP exposure markedly reduced plasma testosterone levels and downregulated crucial testosterone biosynthesis genes (StAR, P450scc, P450arom, ER, FSHR).

Conclusions:

• Concentrated ambient PM_2.5 exposure negatively impacts mice sperm quality and morphology.
• The observed reproductive effects are likely mediated by a decline in testosterone concentration and impaired testosterone biosynthesis.
• Findings highlight the potential reproductive risks of PM_2.5 pollution in male populations.